[PATCH 2/3] powerpc - Separate the irq radix tree insertion and lookup

Sebastien Dugue
2008-08-04T13:58:50Z

irq_radix_revmap() currently serves 2 purposes, irq mapping lookup
and insertion which happen in interrupt and process context respectively.

Separate the function into its 2 components, one for lookup only and one
for insertion only.

Signed-off-by: Sebastien Dugue <sebastien.dugue@bull.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <michael@ellerman.id.au>
---
arch/powerpc/include/asm/irq.h | 18 ++++++++++--
arch/powerpc/kernel/irq.c | 46 +++++++++++++++-----------------
arch/powerpc/platforms/pseries/xics.c | 11 +++-----
3 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/include/asm/irq.h b/arch/powerpc/include/asm/irq.h
index a372f76..0a51376 100644
--- a/arch/powerpc/include/asm/irq.h
+++ b/arch/powerpc/include/asm/irq.h
@@ -236,15 +236,27 @@ extern unsigned int irq_find_mapping(struct irq_host *host,
extern unsigned int irq_create_direct_mapping(struct irq_host *host);

/**
- * irq_radix_revmap - Find a linux virq from a hw irq number.
+ * irq_radix_revmap_insert - Insert a hw irq to linux virq number mapping.
+ * @host: host owning this hardware interrupt
+ * @virq: linux irq number
+ * @hwirq: hardware irq number in that host space
+ *
+ * This is for use by irq controllers that use a radix tree reverse
+ * mapping for fast lookup.
+ */
+extern void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
+ irq_hw_number_t hwirq);
+
+/**
+ * irq_radix_revmap_lookup - Find a linux virq from a hw irq number.
* @host: host owning this hardware interrupt
* @hwirq: hardware irq number in that host space
*
* This is a fast path, for use by irq controller code that uses radix tree
* revmaps
*/
-extern unsigned int irq_radix_revmap(struct irq_host *host,
- irq_hw_number_t hwirq);
+extern unsigned int irq_radix_revmap_lookup(struct irq_host *host,
+ irq_hw_number_t hwirq);

/**
* irq_linear_revmap - Find a linux virq from a hw irq number.
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 9bef9f3..ba24efd 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -821,9 +821,6 @@ void irq_dispose_mapping(unsigned int virq)
host->revmap_data.linear.revmap[hwirq] = NO_IRQ;
break;
case IRQ_HOST_MAP_TREE:
- /* Check if radix tree allocated yet */
- if (host->revmap_data.tree.gfp_mask == 0)
- break;
irq_radix_wrlock(&flags);
radix_tree_delete(&host->revmap_data.tree, hwirq);
irq_radix_wrunlock(flags);
@@ -875,43 +872,44 @@ unsigned int irq_find_mapping(struct irq_host *host,
EXPORT_SYMBOL_GPL(irq_find_mapping);

-unsigned int irq_radix_revmap(struct irq_host *host,
- irq_hw_number_t hwirq)
+unsigned int irq_radix_revmap_lookup(struct irq_host *host,
+ irq_hw_number_t hwirq)
{
- struct radix_tree_root *tree;
struct irq_map_entry *ptr;
- unsigned int virq;
+ unsigned int virq = NO_IRQ;
unsigned long flags;

WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);

- /* Check if the radix tree exist yet. We test the value of
- * the gfp_mask for that. Sneaky but saves another int in the
- * structure. If not, we fallback to slow mode
+ /* Note: It is safe to call radix_tree_lookup() here, even before the
+ * tree gets initialized because the struct irq_host is zallocated
+ * and radix_tree_lookup() returns NULL when root->rnode is found
+ * to be NULL.
+ * IOW, for any interrupt taken before the tree is initialized, we
+ * return NO_IRQ.
*/
- tree = &host->revmap_data.tree;
- if (tree->gfp_mask == 0)
- return irq_find_mapping(host, hwirq);
-
- /* Now try to resolve */
irq_radix_rdlock(&flags);
- ptr = radix_tree_lookup(tree, hwirq);
+ ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);
irq_radix_rdunlock(flags);

- /* Found it, return */
- if (ptr) {
+ if (ptr)
virq = ptr - irq_map;
- return virq;
- }

- /* If not there, try to insert it */
- virq = irq_find_mapping(host, hwirq);
+ return virq;
+}
+
+void irq_radix_revmap_insert(struct irq_host *host, unsigned int virq,
+ irq_hw_number_t hwirq)
+{
+ unsigned long flags;
+
+ WARN_ON(host->revmap_type != IRQ_HOST_MAP_TREE);
+
if (virq != NO_IRQ) {
irq_radix_wrlock(&flags);
- radix_tree_insert(tree, hwirq, &irq_map[virq]);
+ radix_tree_insert(&host->revmap_data.tree, hwirq, &irq_map[virq]);
irq_radix_wrunlock(flags);
}
- return virq;
}

unsigned int irq_linear_revmap(struct irq_host *host,
diff --git a/arch/powerpc/platforms/pseries/xics.c b/arch/powerpc/platforms/pseries/xics.c
index d6e28f9..8c7f058 100644
--- a/arch/powerpc/platforms/pseries/xics.c
+++ b/arch/powerpc/platforms/pseries/xics.c
@@ -310,12 +310,6 @@ static void xics_mask_irq(unsigned int virq)

static unsigned int xics_startup(unsigned int virq)
{
- unsigned int irq;
-
- /* force a reverse mapping of the interrupt so it gets in the cache */
- irq = (unsigned int)irq_map[virq].hwirq;
- irq_radix_revmap(xics_host, irq);
-
/* unmask it */
xics_unmask_irq(virq);
return 0;
@@ -346,7 +340,7 @@ static inline unsigned int xics_remap_irq(unsigned int vec)

if (vec == XICS_IRQ_SPURIOUS)
return NO_IRQ;
- irq = irq_radix_revmap(xics_host, vec);
+ irq = irq_radix_revmap_lookup(xics_host, vec);
if (likely(irq != NO_IRQ))
return irq;

@@ -530,6 +524,9 @@ static int xics_host_map(struct irq_host *h, unsigned int virq,
{
pr_debug("xics: map virq %d, hwirq 0x%lx\n", virq, hw);

+ /* Insert the interrupt mapping into the radix tree for fast lookup */
+ irq_radix_revmap_insert(xics_host, virq, hw);
+
get_irq_desc(virq)->status |= IRQ_LEVEL;
set_irq_chip_and_handler(virq, xics_irq_chip, handle_fasteoi_irq);
return 0;
--
1.5.5.1